Added note – the dispersal map in today’s printed edition of the Daily Yomiuri shows the air flow all along the coast south of Fukushima, not north.

The Yomiuri Shimbun

The Meteorological Agency has been withholding forecasts on dispersal of radioactive substances from the Fukushima No. 1 nuclear power plant despite making the forecasts every day, it was learned Monday.

Meteorological institutions in some European countries such as Germany and Norway have been publishing their own radiation dispersal forecasts on their Web sites based on their own meteorological observations.

Nuclear experts at home and abroad are criticizing the Japanese government for not releasing its own forecasts, raising new questions about the government’s handling of information on the nuclear crisis.

The agency is making daily forecasts at the request of the International Atomic Energy Agency. When contamination by radioactive substances across national borders is feared, weather organizations of the member nations cooperate to make forecasts on possible migration of the substances.

The Meteorological Agency has been calculating its forecasts on the migration once or twice every day since March 11, when the great earthquake hit the Tohoku and Kanto regions.

The agency inputs observation data sent from the IAEA–such as the time when radioactive substances are first released, the duration of the release and how high the substances reach–into the agency’s supercomputer, adding the agency’s observation data, including wind directions and other data. The supercomputer then calculates the direction in which the radioactive substances will go and how much they will spread.

However, the agency has only been reporting the forecasts to the IAEA and not releasing them to the public at home.

The IAEA analyzes the data from Japan by adding observation data from other countries it similarly asked for cooperation, such as China and Russia, and notifies nuclear authorities of countries, including Japan, of the results.

Whether to announce the IAEA analysis is left to each government’s judgment. The Japanese government’s Nuclear Emergency Response Headquarters has so far not released the IAEA analysis.

“Japan has its own Education, Culture, Sports, Science and Technology Ministry- operated System for Prediction of Environmental Emergency Dose Information (SPEEDI) for dispersal forecasts. The government in its Basic Disaster Management Plan defines forecasts by SPEEDI as official forecasts,” a Meteorological Agency official explained.

“We don’t know whether the IAEA basic data the agency uses for the forecasts really fit the actual situation. If the government releases two different sets of data, it may cause disorder in the society.”

However, the SPEEDI forecast was announced only once, on March 23. The Nuclear Safety Commission has been refusing to announce subsequent forecasts. “We can’t do it because the accuracy is still low,” Seiji Shiroya, a commission member said.